A weak dollar means, by definition, that foreign currencies have appreciated relative to it.
The question of what a country should do when the dollar gets weak is an interesting one. We find China stubbornly resisting attempts to make their money worth more dollars. And this seems to be the path all countries are following [or would like to follow], devaluing their own currencies to keep at the same level that they were with respect to the dollar.
And the rationale of course is to stimulate exports. But it is just another of the economic absurdities flying around.
What is the purpose of exports? To get foreign money. And what is the purpose of getting foreign money? To buy foreign stuff.
OK, let’s look at what happens in a devaluation, from all sides.
Say that the Confederate States of America has one Confederate Dollar, tradable for one US Dollar. So if they make something that costs them one Confederate dollar and sell it for one US dollar, they can buy whatever one US dollar can buy, say a copy of the Wall Street Journal.
Now say the US dollar devaluates and is worth half a Confederate Dollar. Then Southerners can take the same old Confederate dollar and get double, two Wall Street Journals. So they win. In fact anyone in the South can now buy double what he used to from the US. Walmart South stores will open, selling cheap US goods in the South. Everyones standard of living rises in the South.
Of course there is a little catch. Of the hundreds of millions of Southerners who gain tremendously from the US dollar devaluating, there is a small group who might lose. The Southern exporters. Their exports to the US will be more expensive for US citizens to buy, so they will probably sell less in the US. The doubling of their profits [two Wall Street Journals instead of one] might not be enough to offset the lower amount of sales.
The US citizens lose big time, because they can no longer afford Southern products.
Just to complete the picture, US exporters will sell more in the South, so it looks like they are gaining. But what will they get in return for the thing it cost them a US dollar to make? Half a Confederate dollar. And half a Confederate dollar still only buys what it used to of Southern products. Meaning the US exporters sold more, but got paid less.
Bottom line: If a country devalues its currency to “stimulate exports”, all its people lose big time. The whole economy suffers; the standard of living drops. Even the exporters may lose since they are getting less per item than they used to. If they want to increase sales by selling cheaper, they could just drop their prices without screwing over the whole country with a devaluation.
As to the claim that foreign investments will drive up inflation, we Austrians know that inflation is by definition more local money printed. So that foreign investments have nothing to do with inflation. As for driving up asset prices, that sounds right. More demand [coming from foreigners] raises prices.
So that indeed the local govt wont be able to drive up prices like it always does by printing money, because added to the price rise already caused by increased foreign demand, it may be more than people can handle. But that has nothing to do with devaluating their currency, which is always bad for the people.